This invention relates to a control system of a vending machine, and more particularly a coin control unit generally termed a changer unit.
The coin control unit of a vending machine is the most important portion that accepts inserted coins, makes a judgment as to whether a merchandise selected by a purchaser is vendable or not based on the inserted coins, pays out a change, etc. Generally, the coin control unit is constituted by a mechanical unit that selects, accepts and returns inserted coins, and pays the change, and a circuit unit that controls the mechanical unit and executes an arithmetic operation necessary for the control.
An important problem of the vending machine is how to increase the chance of vending. In other words, how to increase the chance of vending by minimizing as far as possible the chance of rejection of vending due to shortage of the change. To this end, it is essential to always correctly know the amount of the coins stored in the machine that can be used as the change and to accurately judge as to whether vending is possible or not based on the stored amount the coins for the change. For example, although vending is possible in view of the sufficient stored coins that can be used as the change, if a misjudge is made such that vending is not possible due to the shortage of the stored coins the potential chance of vending will be slipped.
The prior art vending machine has generally been constructed such that a judgement is firstly made as to whether the vending requires a change or not and that where the vending requires the change, the vending is made possible only when the amount of the stored change coins exceeds a predetermined number. The judgment as to whether the amount of the change coins exceeds a predetermined number or not is made by the output signal of an empty switch installed at a predetermined position of a change coin tube. In this construction, it is necessary to install the empty switch at a position above a position corresponding to the maximum amount of the coins required for a change. Therefore, vending that can be made with a change less than the maximum amount of the change is judged impossible, which is of course an undesirable judgment. Especially, where a plurality of types denominations of the change coins are used so that it is necessary to install a plurality of empty switches for a plurality of change tubes, chances of vending would be lost more frequently. It means that even though the vending is actually possible it would be judged that the vending is impossible. In addition, installation of empty switches for respective change tubes increases the necessary space.